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10 horrible critters that will ruin your holiday

Bilharzia worm One of the better known critters on this list, Bilharzia worms are parasitic larvae that live in freshwater snails with a tiny, hook-like claw, used to get under the skin of people. Literally. They then grow into worms, which can be fairly easy to get rid off, but the eggs they lay can remain. To avoid Bilharzia - one of the world's most common illnesses - it's best to avoid swimming in lakes in Africa or the Nile. Lisa Grainger, a Telegraph Travel writer, described her experience of the infection, also known as schistosomiasis: "I was exhausted for about three days, it felt like someone had put me in a coma, all I could do was sleep".